This invention concerns microvalves made of many layers of material of which at least one layer is a silicon mounting frame and the device is provided with an inlet, an outlet, at least one valve seat and at least one closing member, as well as means for electrostatic actuation of the at least one closing member.
A microvalve built in essentially three layers is known from British Patent Disclosure 21 55 152 A and the corresponding U.S. Pat. No. 4,581,624. In that device an inlet and an outlet as well as a valve are provided in a silicon carrier layer. An intermediate layer is provided on the silicon carrier layer and on that intermediate layer a cover layer is applied. These layers form an internal space that provides the pressure medium connection between the connections to the outside of the device. The cover layer is constructed to serve also as a membrane in which there is integrated a closing member cooperating with the valve seat. In the operation of this microvalve an electrostatic actuation device disposed on the membrane may not overcome either the forces of the resilient membrane or the pressure of the fluid present at the input, because the membrane closing the valve seat faces and is subject to this pressure without compensation.